The present invention relates to a thermal transfer ink and a thermal transfer element using the same.
Hitherto, there has widely been employed a thermal transfer ink for use in a thermal transfer element, which ink contains a coloring agent and a heat-meltable vehicle which is composed of a wax, or a wax and a heat-meltable resin.
However, in the case of a solvent coating type thermal transfer ink containing a wax which is dissolved or dispersed into a solvent for application, the coating liquid thereof needs to be kept under heating at a temperature higher than room temperature in the preparation and application thereof due to the poor solubility of the wax used. In removing the solvent by drying after the application, the solvent does not readily vaporize, i.e. the drying property of a wet coating of the coating liquid is poor, which causes problems such as a prolonged drying period and formation of an ununiform ink layer.
The dispersibility of coloring agents, such as carbon black, to waxes is generally poor, which causes agglomeration of the coloring agent in the ink. For this reason, both inks of solvent coating type and hot-melt coating type have problems such as poor ink stability, poor coating property and difficulty of forming printed images with a high density.
In view of the foregoing, it is an object of the present invention to provide a thermal transfer ink which is excellent all in solubility to a solvent for application, solvent drying property, ink stability, coating property and printing property (print image density) in spite of using a wax as a vehicle, and a thermal transfer element using the same.
This and other objects of the invention will become apparent from the description hereinafter.